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Here's the output of cat /proc/cpuinfo:

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 0
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

Why 4 processors are all with the id 0 (processor : 0)?

share|improve this question
    
Is it possible for you to provide the output of gunzip -c /proc/config.gz | grep CONFIG_SMP? (This command may not work depending on your kernel) –  Tom Shaw Jun 4 '11 at 11:26
    
@Tom Shaw ,there's no such file in my system. –  kernel Jun 4 '11 at 21:32
    
Did you compile the kernel yourself? Do you know the value of CONFIG_SMP (or can you check it from the .config file in the source tree)? –  Tom Shaw Jun 5 '11 at 0:21

1 Answer 1

up vote 1 down vote accepted

Your kernel may be configured without SMP support. See the source for proc.c:

        unsigned int cpu = 0;
...
#ifdef CONFIG_SMP
        cpu = c->cpu_index;
#endif

This cpu variable is then used in the output of the processor field in /proc/cpuinfo.

share|improve this answer
    
what's different whether or not a cpu is assigned a cpu_index? –  kernel Jun 4 '11 at 21:44
    
@kernel: The difference is that it may indicate your kernel has been compiled without SMP support, which would mean you are not taking advantage of all of your cores. Or there could be another reason. That's why I've asked about the CONFIG_SMP parameter. –  Tom Shaw Jun 5 '11 at 0:25

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